Activity at Hekla and The Dead Zone

While we are waiting for Öraefajökull to drop a Christmas present and Grimsvötn to hatch an Easter egg, we instead might get a gift from Hekla. And at the horizon suddenly, a far darker bird looms.

So, once more we must ask and answer the age-old volcanic question; what gives in Iceland?

Hekla

The two earthquakes swarms of Hekla and The Dead Zone. Image from the Icelandic Met Office.

Many people have noticed that Hekla has been quite busy in the last few months. There have been no less than 3 different types of earthquakes there. Or, to be more exact, 3 different locations indicating 3 different things going on at the same time.

Let us start at the top, then go to the bottom, and then cover the in-between.

So far roughly half of the earthquakes have occurred at a depth of no more than 0.1 kilometre. It is easy to think that these earthquakes are dangerous as they are occurring at the bottom of the edifice.

Morphology of Hekla, image by Gaz Dale based on data from the Icelandic Met Office.

In reality, they are just a sign that one of the most common forces in physics is at work. You might even say that it is evidence that our Universe is quietly doing business as usual.

The bedrock under Hekla is slowly pulling apart making the foundation of the volcano fragile. And on top of that fragile cleavage, you have an edifice that has grown rapidly over the last 5000 years (the edifice is not older than that).

At every eruption, Hekla gains quite a bit of height. But, as soon as the show is over and the volcanologists have taken their GPS reading on the top, gravitation goes into overdrive and the entire edifice will start to drop down like a stone into an ocean of lard.

Plot of earthquakes at Hekla since 2011. Image by the Icelandic Met Office.

And it is that downward force that causes those earthquakes at 0.1 kilometre as the rock under the heavy edifice breaks Under Pressure. One can think of Hekla as the perfect Queen metaphor, during eruptions it is singing “We will rock you”, and directly after it switches to “Under Pressure”.

If we go down into the deep bowels instead, we find earthquakes associated with upward movement of magma. These occur at depth around 20 kilometres, or even deeper. As magma ascends towards the edifice it puts the conduit under pressure and the walls crack and groan. These deep earthquakes are among the most important earthquakes in Iceland to keep track of, since they normally herald future activity.

A few weeks ago we saw that kind of activity at Hekla, and it is not surprising therefore that it has become a tad more lively.

Now, if we instead look at the medium level earthquakes we can divide them into two separate categories. The first one would be caused by a pressure increase in and around the magma reservoir of Hekla as the rock surrounding it start to crack. This is also a potential sign of an upcoming activity.

The other type of intermediate depth earthquakes are instead tectonic. The volcano Hekla is a rifting fissure volcano that has formed a polygenetic cone on top of it reminiscent of a stratovolcano. I have dubbed this volcanic class of one as Stratofissure. It is an apt description since the initial phase of an eruption behaves like a classic explosive stratovolcano on steroids, and then it quickly starts to behave more like a large effusive fissure eruption.

Normal Icelandic tectonic activity rarely has any volcanic ramifications, but here these tectonic earthquakes are a sign that the fissure is being pulled apart. And pulling apart the roof of a magma reservoir at a steady pace is not good for magma containment.

Here there is a case of the hen and the egg. Is it the increasing magma pressure that is pushing the fissure apart? Or is it the pulling apart of large tectonic forces that causes magma to ascend upwards?

In this case, we get both hen and eggs to eat. By now this has become a self-sustaining system being pulled apart at the same time as it is being pushed apart. It explains quite a lot of Hekla’s behaviour and characteristics.

In the end, all we can say is that it seems like Hekla is closing in on doing the fandango. But, what exactly the time frame is, well… that is a completely different question. In a geological timeframe, it is probably just moments away. So, it is 30 minutes away at any given time, and those 30 minutes can happily extend into years.

The Dead Zone: Revenge of Elgjá

Image with the major fissure swarms in the Dead Zone, complete with the recent earthquakes. Image by Gaz Dale based on data from the Icelandic Met Office.

Roughly East northeast of Hekla is a zone that is aseismic. It is a bit of an oddity that it is aseismic since it quite literally is the spot where the planet is being pulled apart. Lurking and I dubbed it The Dead Zone, and in the end, we even came up with a good explanation for how it can be so quiet for such a long time before all hell breaks loose.

The area is filled with some of the largest volcanic features on the planet, massive rifting fissure swarms coming out 3 different large volcanic systems. Bardarbunga has the largest rifting fissure swarm, it is sometimes called the Veidivötn system.

Grimsvötn has two different fissure swarms in the area, the most famous is called Lakí. And Katla has one called Eldgjá.

All of these rifting fissure swarms are true giants able to erupt between 15 and 35 cubic kilometres during their rare eruptions.

Since humans settled in Iceland, 3 large eruptions have occurred. The first one was the 934AD 18 cubic kilometre eruption of Eldgjá. In 1477 Veidivötn had a VEI-6 eruption creating 10 cubic kilometre of tephra and 5 cubic kilometres of lava flow.

The last big hit was Lakí in 1783, known as the deadliest eruption to ever happen to humanity. Out of the two million dead, very few died from ash-fall or lava. Instead, it was the ensuing famine caused by a rapid cold onset that killed most people, the second largest killer was the released gas destroying lung tissue all over northern Europe.

Morphology of Eldjá and Katla, image by Gaz Dale based on data from the Icelandic Met Office.

The tally of Lakí was 12 cubic kilometres of tephra judged from distal ash fall found in bogs and ice cores all over the northern hemisphere. The oddity is that very little ash is found in Iceland, probably due to the heat sucking the ash high up and out over the ocean.

It also produced prodigious amounts of lava, more than 15 cubic kilometres.

The large Icelandic rifting fissure eruptions are cyclic in nature occurring roughly 210 – 250 years apart. As some of you may have noticed, sometimes the cycle skips a beat. But, in the end, during one of the cycle peaks, another large eruption occurs.

And it does not take a large amount of mathematical skill to realise that the last eruption occurred 235 years ago.

Iceland is often called The Land of Ice and Fire, but it should be called the land of volcanic cycles. Almost every volcanic area of Iceland has its own volcanic cycle, and all of them are ruled in part of the mightiest of all volcanic cycles, and that is the mantleplume cycle.

Roughly every 170 years apart the mantleplume has a pulse pushing up deep magma from the mantle, injecting fresh material into many Icelandic volcanic systems causing a marked uptick in eruption frequency. A bit arbitrarily we say that the current pulse started in 1996 and that it is peaking about now.

This is probably a bit of conjecture because the deep magmatic earthquakes started after that in the new millennium. This is in the end just a bit of nitpicking, we know that the mantleplume pulse by now is in full swing.

This combination of Iceland’s two largest volcanic cycles increases the probability that a large rifting fissure eruption will occur in the Dead Zone.

Now, let us get into the tectonic nitty-gritty side of things. We know that Iceland is being pulled (or pushed) apart at a fairly steady rate of 2.8 centimetres a year. 2 of those centimetres are taken up in The Dead Zone and up through Vatnajökull.

This does not account for local variations, we are after all talking about continental plate movement averages. So, any given year the in this context small area of The Dead Zone quietly is pulled apart 2 centimetres. We can see that this motion is steady and clear on all GPS stations in Iceland. Locally it can differ a bit, but not that much.

This changes quite a bit during a rifting fissure eruption. All of a sudden a large line extending through 2/3rds of the length of The Dead Zone can pull apart 150 metres in just a few months, leaving immense scars in the scenery.

This difference between large-scale plate tectonic motion and local area tectonic motion is caused by the combinative forces of plate tectonic pull and rapid injection of vast amounts of magma pushing violently apart the land.

Another effect of this is that the least likely candidate to suffer a rifting fissure eruption is the system that last erupted since the tension is all spent in that area. Now, remember that the pent-up tension is not the same as the amount it will pull apart in the end.

In 934 Eldgjá happily rifted 150 meters, but since then the strain has built up with roughly 11 metres. One would then assume that it could not rift on a large scale again, but that is a fallacy since it does not consider the pushing side of the push-pull nature of The Dead Zone.

In fact, the pull part of the equation is the weaker one, since deglaciation The Dead Zone has only pulled apart 240 metres, but the total amount of fissure width combined is believed to be 1500 metres. Quite a difference, on the local scale magma push, is the giant and on the continental-scale, the gravitational pull is the winner. Always remember the scale at hand.

Now, let us just assume that the cycle will not skip a beat, after all, we have two cycles at the same time. Which volcano of our 3 usual suspects would be The One?

Lakí is a bit of a long shot. First of all, Grimsvötn is mainly a major central volcano erupter. Out of the roughly 100 known eruptions, only 3 has come out of the fissure swarms of Grimsvötn. Also, it is also the most recent to suffer a large rifting fissure eruption. The upside is that Grimsvötn is the world record holder of magmatic influx, so it has by now amply received more magma than it expelled as lava during the 1783 eruption. In the end, I still judge this as the least attractive candidate, it seems quite content with causing ever larger explosive eruptions at the moment.

Bardarbunga is the champion of rifting fissure eruptions in Iceland. 14 of the 20 known rifting fissure eruptions in the Dead Zone has stormed out of Bardarbunga, and that includes the 3 largest. The problem here is that it erupted in 1477, so the tension is perhaps not enough. Also, the Holuhraun rifting fissure eruption in 2014-2015 removed a lot of pent-up lava from the system. I would say that we are at least a decade away before Bardarbunga could get into the fray due to low systemic pressure.

Katla, on the other hand, has had a long repose time since it’s last eruption, on the 12 of October Katla celebrated its centennial since the last known eruption. At the same time, we know that Katla has had 3 major intrusive phases in the last 3 decades, and there are signs that a fourth intrusive episode is underway as evidenced by renewed earthquake activity below the 20 kilometre mark.

Combining this with it being the volcano that has gone the longest without a rifting fissure eruption places Katla and Eldgjá in the pole position until another one bites the dust.

Well, don’t stop me now. As I mentioned above, The Dead Zone is quite aseismic. Every little earthquake out there will have the Conoscenti raise their eyebrows hoping for a bit of I want to break free from one of the fat bottomed girls.

I also mentioned above the importance of deep intrusive earthquakes.

So, what got me writing today is that a deep intrusive earthquake episode started at 21 km depth and faulted up to 16 km depth in a direction heading towards Eldgjá. The event started at 09.28,10 Icelandic time and lasted 9 minutes.

At 09.56,57 Icelandic time, the first of 3 earthquakes (so far) occurred at Eldgjá. As such it is not such a stretch of the imagination to think that the initial upwards moving intrusion injected directly into the fissure swarm. If this piece of conjecture holds up to scrutiny we should in the next few days to weeks see more earthquakes out on the Eldgjá fissure swarm.

A bonus volcano

And as I was writing this I also noticed that another of the usual suspects has changed its behaviour. Obviously, it had to be Grimsvötn. Since the last eruption in 2011, it has been quite a bit in the doldrums as it quietly inflated towards the next eruption.

Morphology of Grimsvötn, image by Gaz Dale based on data from the Icelandic Met Office.

This happy little swarm is happening right south of Grimsvötn proper in the direction towards the sister volcano Háabunga. This is in an area that has caused repeated trajectory changes at the GFUM GPS-station in the last few years.

It has though not had an awful lot of earthquake activity in the form of Cumulative Seismic Moment energy release. CSM is historically a very good tool to predict when Grimsvötn is ready to erupt, so a sharp increase in Cumulative Seismic Moment energy release is a good sign that Grimsvötn is once more rapidly cooking up another batch of Bohemian Rhapsody.

Grimsvötn 15 day earthquake plot. Image by the Icelandic Met Office.

I will guess that the volcanic version of Montserrat Caballe is not more than a couple of years away from erupting, and as usual, it will be noticed even in Barcelona.

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221 thoughts on “Activity at Hekla and The Dead Zone”

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Spell-checking and grammar correction will hopefully soon be done by a friendly Word-dragon.
I accidentally pushed the publish button before it could be done.
And now yours truly is to tired to do it on his own after a 10 hour day and speed writing the article in about an hour.
Mea Culpa!

Additionally, the level of proof reading is directly dependant on the authors attitude at the time. If we are time strapped or don’t concider it as important as the material itself, the reader is left to use some cognitive ability to glean meaning from the info.

And that is in addition to whatever colloquial expression is used. We don’t concider our readers to be complete idiots that have to be spoon fed. We approach it as if they are smart enough to understand.

One thing I want to know is how much lava is erupted yearly on average. Explosive volcanoes get all the glory but effusive eruptions are far bigger compared equally, in effect having holuhraun followed 3.5 years later by the equally vigorous Leilani eruption, and then sierra negra joining in is equivalent to having a pair of VEI 7s with the second occurring simultaneously with yet another VEI 6+. Probably if you add kilaueas high end supply to the upper number for grimsvotn you get 1.2 km3 per year, which is probably at least half the world total.

Carl if you get the energy contained in that much lava cooling to ambient temperature (which, granted, will take a long time) you end up with a very big number in joules, in fact the number is bigger than the size of the tambora eruption in megatons. Leilani was a total thermal energy release equivalent to 960 megatons of tnt, holuhraun was about 1450. Tambora was 800 megatons, it was a bigger eruption because it happened in a day rather than 3 months, and so was more destructive. Eruptions like Tambora also derive a lot of their volume from preexisting rock rather than new magma and felsic magma is half as hot as basalt in Hawaii, so there is already way less thermal energy. This is why I have repeatedly said kilauea is far and away the most powerful volcano anywhere on earth, by the end of this century it would have received many more km3 of lava and erupted most of it, while any volcano capable of a VEI 7 will be out of action for centuries or millenia and take even longer to repeat a big blast. In the Holocene kilauea has been supplied with anywhere from 700 up to over 3000 km3 of lava and most of that would have been erupted. No other volcano in the Holocene has even come close to an eruption as big as that, and at the upper number even toba falls short. Kilauea is basically grimsvotn unrestricted by passive rifting, or a flood basalt that leaks instead of flooding.

If you want an idea of what Kilauea will be like, 2/3 of mauna loas 85000 km3 volume formed over a 100,000 year period ending just before the Holocene started, that is a base supply of half a km3 every year, and even if only half of that erupted you would get a 1950 every year. Kilauea currently has less overall output because it’s rift is very long but as it gets bigger and more active the rift will be more full of magma all the time so the eruption to intrusion ratio could be close to 1/1 or over 50% eruption rate from depth.

True that none of these eruptions will ever alter world climate but the only way to compare all eruptions fairly is through energy of the magma, and effusive volcanoes really show their true nature that way. It’s like gunpowder vs burning petrol, gunpowder explodes, petrol doesn’t (usually), but petrol has much more potential energy.

0,5km3 every year coud be a likley number for Grimsfjöll
the mar ridge rift… handicaps that volcano alot…. as alot of magma goes into filling the space between the litospheric plates. But this is why Grim haves a +500km3 deep magma resovair of fully eruptible basalt magma

I remeber you told me long ago there is 800km3 of eruptible magma inside the entire vatnajökull?
But holy moly for Grimsvötn 500km3 inside its deep parts… thats 500 possible happy holhurauns jumping around inside stinkvötn. Grimsvötn may be the only volcano on earth now with capacity of a 100km3 lava rift event… but that seems rather unlikley and once every 200 thousand years

I think Veidivotn did some 30km3 some few thousand years ago (Thjorsarhraun). It rifted all the way in the dead zone.

Maybe 40km3 would the upper limit possible.
I don’t think it’s possible more than that.

But shield eruptions could erupt slightly above that if they develop a feeder. Like the hard to spell Theistjareyarbunga volcano.

Explosive eruptions could also near 20-30km3 on rare occasions. It happened in Torfajokull few dozen thousand years ago. Maybe in Grimsvotn in early Holocene. That’s near 10℅ of their chamber. More seems impossible. Carl would be able to comment on this.

Grimsvötn coughed up 150km3 in 5 eruptions during a 500 year span. The 3 largest constructed the calderas of Grimsvötn, and the biggest of the bunch gouged out the eastern ear of the Mickey Mouse shaped caldera that the phase produced. That caldera part is still destroyed.

Thanks Carl. Eldgja erupted in 939, not 934, both according to the tree ring record and the ice core record calibrated to the Korean eruption of 945. An interesting bit about the dead zone is that each rift can be fed fro either side. Eldgja reached to close to Vatnajokull, and at the last stretch erupted a magma with some Vatnajokull content. It had reached an older pocket of magma inserted from the other side. Eldgja erupted into a pre-existing rift, and it seems this rift had created pathways to both sides. Laki probably not.

It is possible that every eruption in this region needs to create a new pathway. The previous one was filled with magma, and (like polyfiller) once solidified becomes stronger than the rock on either side. A new intrusion will tend to break the rock rather than the polyfiller.

Grimsvotn perhaps cannot be excluded. It has a smaller caldera than the other main systems, and this may mean it had more refilling. There was a bit of a southwest trend in the swarm, so that axis of weakness (the spreading axis) is still present in the stress field.

I think it is maybe more likely that the end of the eldgja dike reached the main vatnajokull magma chambers, the massive ones under grimsvotn. However I think it is noted that relatively few eruptions at that time had come from vatnajokull, so maybe the area was under pressurised and so eldgja didn’t cause a knot her eruption there. Still even if that isn’t the case the magma could have been very old, and the dikes probably never completely solidify. On kilauea some of the 1955 lava was prehistoric, as was possibly fissure 17, and while it is true that the east rift of kilauea erupts about 100 times as often as the dead zone, the dead zone eruptions can be much bigger, so the amount of energy that goes through each system is comparable and in addition the dead zone is much deeper as it is a fundamental plate boundary rather than a crustal deformation zone. Kilaueas deepest extent is maybe 12 km near the summit and eruptions there all originate at least within the general area of its summit complex even if they happen tens of km away like this year. In contrast the dikes feeding the big rifting eruptions in Iceland could easily be twice that depth at over 20 km and still remain entirely inside the crust, and there is a debate whether that even happens either, as some eruptions probably reached the mantle. Especially the violence of the opening stage of the skaftar fires seems to be indicative of there being a more direct link, the dike to holuhraun was also very deep but that was fairly typical in eruption and closely resembled the eruptions in Hawaii and other basaltic hotspot volcanoes, skaftar fires opening phase was a basaltic plinian eruption like the 2011 eruption and that doesn’t seem like something which could happen without a really deep direct source. The composition of the skaftar fires lava was also very primitive like the 2011 magma.

I guess when you get a volcano which has done large rifting fissure eruptions and usually erupts 2-4 times a century go a full 100 years without erupting, seeing said volcano start showing deep magmatic quakes on its fissure swarm which is otherwise totally aseismic and prone to flood basalts is really not expected at all and could turn into a black swan. Katla is not going to go VEI 6 pinatubo like the media thinks, but a rifting fissure would be way bigger and much more damaging.

The problem is that even though it was almost 10 years ago now someone will definitely try to link it with the supposed connection to eyafjallajokull and go all doonsday predictive…

A bit on the predictability of Black Swans. → Mostly true, but in actuality, the probability for the event happening is so low that it is erroneously assumed to be zero. That’s how they are able to sneak up on you. Even if one or a few people think they are likely, the fact that the overall accepted wisdom of it not happening is the dominant choice of whoever is in control is what is what matters in this regard.

Fukishima was an effective Black Swan even though Kiyoo Mogi thought there was a seismic threat to the nuclear sites. Like a plot device from a SciFi movie, no one heard him out.

And when you look at his field of research, he was perfectly positioned to see it coming. He was gathering data from GPS all over Japan and could probably see the massive crustal flexure penning up the stresses prior to the Megathrust quake. And for you Pacific Northwestern types… that is exactly what is going on under your feet right now. → Stress build up. In my opinion, TGMcCoy was the smartest of all of you. He moved from the hazard zone while the highways weren’t crowded. Probably beat the rush by several years.

My Chicken@!%# mantra works in more than just volcanic calamity. You’re best bet for survival… “Don’t be there.” If you “have” to be there, and you don’t have a good workable plan on how to get out… you probably aren’t going to make it. Good-Will only goes so far in a catastrophe, and mankind is typically called an apex predator for a reason. No, I’m not saying that people will eat you, but taking your stuff is “fair game” when it comes to survival. It usually takes a starvation scenario and somewhat flexible morals before cannibalism sets in.

Do some of the small basalt eruptions bear hekla count as eruptions from vatnafjoll?
I remember you saying that vatnafjoll was very productive until around the start of the historic period when hekla began growing much faster and so vatnafjoll became dormant, but could the smallish eruptions like 1913 have been from it?

Is this correct?
Grimsvötn maybe a trapdoor caldera when it comes to eruption mecanism.
Just like Sierra Negra. Magma accumulate in grimsvötns upper magma chamber, thats a flat massive sill laccolith form thats feed by an open conduit. As the magma chamber expands.. it expands and cracks the sorrounding rocks causing earthquakes. It also inflates the caldera
When the pressure gets high enough .. the magma goes through the ring faults in sourthen caldera and erupts. 1998 , 2004 and 2011 occured very close to eachother, maybe a more permanent eruptive ventile is forming there.

But if it is like that… there should be lots of earthquakes around the faults in the caldera floor slab over the expanding magma chamber in Grimsvötn. Thats what we are not seeing before a grimsvötn eruption.
Grimsvötns magma system is quite poory mapped I think.

It’s still to young to go caldera. It would need at least another 500 years to build up the edifice large enough to sink into the ground efficiently. Question right now is if this will end up as an atypical eruption outside of Heklugja proper. Currently the seismicity is slowly meandering away. So, could be entirely effusive and small scale.

Otherwise I would go with something in the range of VEI-3 to VEI-4. Ie, the usual hellish stuff.

I agree. Hekla does explosions (big ones) but followed by fissure eruptions within a few kilometers (which is how it build itself up). If it hoes caldera, it will be because of a more distant fissure draining the magma chamber. That is not close to happening though. It is still growing.

Hekla wont go caldera yet… Hekla will continue to grow into something that looks like Eyfjallajökull maybe and then when its mature… it will go evolved plinian and form calderas… it will also grow tall and cold and develop its icesheet. In the end Hekla coud end up into something that looks like Torfajökull when its really old.

Vestmannaeyjar will evolve into something that looks like the Reykjanes Peninsula in the future. Today its alkaline basalts in Vestmannaeyjar .. low degree of partial melting
In the future the partial melting will increase there alot.. and it will change to the Thoelite Basalt series

I guess there is little highly alkaline magmas in Iceland…
Partial melting in Iceland is too high and too shallow for anything like Nephelinite to form
I guess the most alkaline Iceland can do is Alkaline Basalts and some Trachytes.

The quakes at Hekla are at interesting depths. They are seperated in two areas. The south areas are “deep”, 7-9 km deep. The area to the north is “shallow” quakes. 0-2 km deep, and are in line with the Hekla fissure line.

If you plot the quakes in 3 dimensions, it looks a bit like they are all on a single plane that cuts right through Hekla. I don’t think it’s exactly in line with the Heklugjá fissure, but I could be wrong since I don’t have a map included in my plot, only clusters of old quakes to orient myself. I don’t really have time to do this since my workload is killing me right now…

Tomas, did you plot the north quakes at 2km deep or at 0? Also is that 2 km from the surface or 2 km ASL? If its sea level you would need to add 700 m on top of each depth.

We also need to remember that Activity at Hekla has never been plotted as well as it will be now. The net of seismographs over Iceland has were not there the last times she erupted. This is all first time knowledge.

I always use the depth number directly from the list. I’m not sure what the reference level is.

Here are a few samples. I added a least squares fitted plane in the plots. Note that I used the longitude, latitude and depth values, so x,y and z are not equal in scale. This means the least squares penalty is a bit biased between the different dimensions.

It may also just be the base web browser blocking mixed http/https content. Try it in a different browser or accept any mixed content settings. I would investigate more but I’m currently debugging a linux/freeradius server and losing the will to live…

It’s okay, I just got done hanging a network. First time I ever actually had to use an Endoscope to find the freaking cable in the wall. But, had I not had it, I’d still be there cursing and fishing in the blind.

It looks like there is a lot of activity along the fault line of the 1912 quake (15km west of Hekla), then there is a diagonal stretch of quakes leading SE towards the 1987 Vatnafjöll quake area, and then some quakes along that fault line. I think it is along this fault line yesterday’s activity was centered.

There was an eruption in 1913, it happened from a fissure that extended from hekla up towards the northeast. It wasn’t a really big eruption but it shows that heklas entire fissure swarm is active and can erupt well beyond the mountain itself.

That eruption is discredited as a Hekla eruption since the magma does not match any known real Hekla sample. There are quite a few false positives in the records of the GVP.
Here is an old piece I wrote based on field notes by the world leading expert on Hekla, Eric Sturkell, it could do with a bit of updating. But, it explains in broad strokes the difference between Hekla eruptions and non-hekla eruptions with a rather nice analogy that could be useful to understand the difference.

And here is an interlude for Lurking…
A Swede has invented a 2.9 million scoville sausage. Currently known as the strongest sausage on the planet. Only 13 people have so far succeeded in finishing an entire sausage.

I wants a lava lake in Iceland… there was when Trölladyngja and Skalderbreidur and Theistareykjarbunga was active. Lava Lakes are awsome.. tops of magma chamber systems
The only recent lava lakes in Iceland was Surtsey and Holuhraun and they where rather short lived
The largest lava lake for now is Nyiragongo again… after Halemaumau drained

It is with the force of stupidity – an irresistable and unstoppable force. The speed he is given on the way up is close to the speed he has on hitting the ground (ignoring a bit of air friction), I think about 3-4 m/s. I would guess the initial force is around 4g. However, the deceleration is less: he manages to slow himself a bit by hitting the ground bit by bit. His brain seems undamaged but it is hard to damage a vacuum.

Here are a few pointers to what a real Hekla eruption is like, and what to expect.

1. Hekla has the most violent start of an eruption of any volcano on the planet. You won’t second guess yourself when it goes off.
2. If you are to close you have a couple of seconds to be amazed, after that you are pulped by the shockwave.
3. How violent? Well, Hekla has the distal lava bomb kill record. A farmer 32 kilometers away got his head taken clean off by a lavabomb.
4. Half of all people in Iceland will drive like madmen to get to one of the overlook parking spots to watch the greatest show on earth. Those safe parking spots are surprisingly far away, people from Iceland don’t drive closer. There will be Icecream sold there.
5. Hekla is the name of the mountain, the actual name of the volcano is Heklugjá, it is a 7.2 kilometer long fissure bisecting the mountain. Any eruption outside is not a Hekla eruption.
6. The lava will be incredibly weird and should not exist in Iceland.
7. Hekla does not huff, puff or smoke prior to an eruption. It goes from quietly ominous to hell opening up in seconds. If not, you are wrong.
8. If you have doubts about if Hekla is erupting, Hekla is not erupting.

If not all 8 things above is true, there is no Hekla eruption.

The closeby effusive only eruptions are related to this being a part of the South Iceland Fracture Zone, it is an area of many rifts and faultlines, sometimes lava comes oozing out of those cracks. That lava will not be of the Hekla type.
Next rule of Hekla. Vatnafjöll and Hekla are two completely different volcanoes. Do not ever confuse those two. The lava is not at all the same, Vatnafjöll erupts lava resembling Eyjafjallajökull basalt. Hekla erupts Alkaline andesite with extreme fluorine content and loads of other weird byproducts hinting at a subducted slab being involved somehow.

Number 8 is probably the best rule of all. It’s not gonna mince around about it.

And of you are standing up there, you MAY get about 15 minutes warning from the ground shaking. An alert from IMO to your cell phone is probably gonna give you 60 minutes if someone is watching the seismo or strain meters. I think Hekla 2000 was preceded by an empty cup of coffee. “Hey! Look at that!”

Hekla is a basaltic andesite to normal andesite with a very high gas content and fluorine content.
An Alkaline Andesite is called a trachyte.

Hekla sometimes also do basalt.
Heklas andesites are quite fluid for being an andesite.. its likley these lavas are mouch hotter than their subduction zone andesite relatives.

Hekla eruptions are often zoned compostionaly with the highest sillica melt on top and more mafic materials lower down in the volcano.
1948 started as an andesite and basaltic andesite… but at the end of the eruption in 1948 the lavas turned into a viscous basalt.

I think the lava on hekla is probably around 1000-1050 C. Fissure 17 lava was an andesite at that temperature and it looked very similar to the lava in a lot of heklas eruptions, although it had a lot lower eruption rate than hekla does in its opening stages (10-20 m3/s vs 5000 m3/s). At that temperature the physical difference between basalt and andesite seems to be pretty negligible as they both tend to form flat pancakes of lava, and a’a flows if there is a slope. I think most andesites at other volcanoes are much more viscous because they are also much colder.

Fluorite is added to metal ore slag to make it less viscous, fluorite is CaF2, so maybe the fluoride content of heklas lava could have a bit of a similar effect. I brought up this idea a while ago, but I think this is pretty unlikely now that andesite of similar properties to hekla has erupted at kilauea, and kilauea was recently studied in high detail for gas composition and found to have below average fluoride levels.

I would suspect that any magma heated to over 1000 C would appear to be quite fluid, maybe not as much as basalt but glass made directly from melting sand is very similar to rhyolite and it flows easily at 1000 C. I guess that would fit very well with the idea of toba being mostly effusive, maybe it had a deep chamber and constant feed to smaller and much more active stratovolcanoes above it. It might be possible then for other potential tobas to be sitting in any similar setting. An event like it should be called a flood rhyolite. A comparitively tiny version of that could be a normal obsidian flow like the ones in long valley or newberry, or puyehue in 2011.

At the start of eruptions Heklas lava flows tends to be very impressive indeed … with crazy eruptive rates!.. imagine a 16 meters high wall of basaltic andesite comming as faster than fast walk speed down the steep slopes! It crushes everything in their path
When the lava flows reach the plains they slow down and the eruptive rates slows alot after the first day. 1947 had crazy eruptive rates! over 10 000 cubic meters a second.
It takes alot of force to make andesite move like that, since it is a very viscous fluid.
Heklas lavas are around 60 to more than 130 times more viscous than Hawaiis

Andesites, Dacites and Ryholites can be foud in small ammounts in Iceland
Thats beacuse of magma diffrentiation…the basalt collects in magma chambers in the thick icelandic crust.. and evolves and crystalizes over long time.. forming evolved melts.
Heklas lavas is in my own opinion nothing strange at all

Still basalt makes up over 90% of the eruptive materials in Iceland
Iceland is a big pile of basalt lavas thats keept bouyant and above sealevel by that mantle plume

Still the lava flow speed of Heklas andesites amaze me
the first hour in 1947 had lava and tephra ejected at a rate of about 23,000 cu. meters per second.
The gas pressure must have been phenomenal
The lava moved very quickly down to the plains below despiet its very high viscosity
That must have been a terryfying sight!
imagine a wall of glowing rubble comming towards you at walking speed
These are massive Aa flows they ca be over 10 meters thick

Snæfellsjökull is another iceland volcano that have made evolved lavas
Thick and massive Aa and even blocky flows from that one.
If I remebers right here…its alkaline too.. with lower degree of partial melting and greather depths
Thats a great place to look for Phonolites and Basanites… IF they exists in Iceland.
A phonolite is basicaly a very very alkaline version of andesite that goes further into alkalinity than the trachyte does

Perhaps I am boring, but Haukaladur station west of Hekla continues to show unusual signals on its drumplots. This station is not far west of the recent low-level seismic activity near the volcano.
OK, I am less that a half-baked expert, nay – a weevil among experts. But from around 23:00 there’s a lot of pop and rumble that looks like gas on the move, quietly cracking rock and moving around. Not to mention the ‘soft’ quakes earlier in the day. In due course (eventually), might we see a south-west vent open up near Hekla, extending the fissure in that direction?

And before the media dip$h!^s shows up and tries to make an alarmist article about Hekla… REMEMBER. The seismic network monitoring Hekla has increased in sensitivity by many orders of magnitude since 2000.

Many of the quakes that are being discussed here were undetectable 18+ years ago. Just because we kick ideas around about what could happen, that doesn’t mean it will happen.

The word “sensitivity” is bolded (above) specifically because that is why we are seeing more quakes near Hekla. It is not necessarily because of increased activity. That doesn’t rule it out, but it also doesn’t make it so. No amount of wild rhetoric or wishful thinking is going to make it do anything other than what the prevailing seismic and magmatic conditions dictate.

Volcanoes don’t care about your byline. IMO are the ones you should seek if you want an official opinion about what the experts have to say before penning alarmist drivel. Hekla is a nasty enough volcano without your help.

If you want to do something useful, talk about the technological achievements and hard work IMO and associated researchers have done trying to uncover the secrets of these volcanoes. (Like WHY does Hekla show such odd chemistry in its eruptions? A melting plate shard from when a subduction zone existed in the Iapetus Ocean? Something else? Why is Iceland so thick? (Thicker than most oceanic volcanic islands) Try to answer those questions and you are almost assured to get curious readers. As for the volcanoes, they will erupt. → Eventually. It’s nothing really new, That’s why they are there.

Sure, your editor wants something riveting and exciting… Give em something new and fresh. Not the same-old OMG everyone is gonna die bullshit. Now if you find something clear and concise that says people are in peril, and it comes from an authoritative source, by all means, write about it and spread the word. But if it’s just hype… many will just yawn and go away. And some of us will laugh our arses off at your ignorance and speak of you in a derisive tone. (And will probably never take anything serious that you ever have to say in the future.)

Remember the landslides in Hokkaido triggered by the earthquake in September?

It has now been found that the landslides were in layers of ash and pumice, which were erupted from Tarumai volcano, 9000 years ago. The layers are 1.5 meter thick and after all this time, still dangerous.

It will be more than creepy when it erupts. Maybe it won’t be as big as eldgja or laki but pretty much every eruption that has happened there is big, at least 0.5 km3 up to 10 km3, and then you get the 3 big ones which are over 20 km3 DRE. Very notably, two of those have happened in the last 1500 years, in general the frequency of rifting fissures has increased over the Holocene, compared to lava shields which are mostly older than 8000 years. It is now actually more likely that another big rifting fissure flood basalt will happen than a long lived lava shield.

Assuming eruption rates similar to pu’u o’o (5-10 m3/s), the biggest lava shields in Iceland could have been continuously active for centuries. Given their frequency in the early Holocene, it is likely there were many points where one shield overlapped with another in eruption, creating a situation of near continuous eruption over many centuries. I suspect not all of the eruption was continuous though, probably there were a lot of pauses as well as periods of much higher effusion rates with big flows, some shields are the sources of 100+ km long flows so this is likely.

Given that vatnajokull is rapidly melting there could be more shields there in the future. Bardarbunga has already shown it’s potential with trolladyngyia. Grimsvotn is a different beast entirely though, I see it doing more of a series of repeated flood basalts in a small area, kind of like a version of hekla made of lava flows in the km3 range. This could be termed as a ‘flood shield’, although the bigger eruptions probably would I Clyde a lot if ash so it might end up being a weird stratovolcano variant. It would be like 2011 without ice. That would have been an incredible eruption to witness de glaciated, probably still a plinian eruption at the biggest vent but there would have been massive flood lavas too, 1 km3 in a week, 25 times faster than holuhraun, maybe even higher than the peak of the skaftar fires. If it wasn’t just going to be explosive anyway the only thing I can think of is that it would have been like the common erroneous depiction of a volcano with a plinian eruption and massive lava flows at the same time.

I remember seeing grimsvotn 2011 on the news when I was 12 and thinking that looks pretty interesting, before I went to school, only now do I realise the significance.

Yes Grimsvötn 2011 was totaly bonkers! .. its basicaly almost 1km3 erupted the first 24 hours. Most of the 2011 basaltic plinian was erupted the first 2 days.
The skies turned dark with black mammatus and tephra.
1996 was pretty impressive too but nothing like 2011.

Grimsvötn is a nasty beast.. its like a male Sourthen Elephant Seal.. always foul tempered and generaly nasty. 8000 years ago Grimsvötn had around 3 basaltic plinian events with 30km3 erupted each. That formed its nested mickey mouse shaped caldera.

Last summer 2017.. I got to see Grimsvötn when I flyed to Iceland, before I flyed into Reykjavik I got to see vatnajökull from my window seat and Grimsvötns caldera
Luckly the weather was amazingly clear that day.
In christmas I will go to Kilauea and meet John Tarson owner of EpicLava
It will be amazing. I hopes… Grimsvötn does not foul my flight to LA.

I have always imagined 2011 ice free… to be a Giant lava fountain collumn from hell
But you say that.. fragementation rates and brute force… will blow the fluid basalt to ash at these speeds and eruptive rates.. even without Ice ?

I compare it to the 1886 eruption of mt tarawera in New Zealand, which was erupting a very primitive basalt even more mafic than the lava erupting in Hawaii or Iceland but it was a VEI 5 with almost no lava flows. Grimsvotn 2011 was probably going to be like that except because it was subglacial it is hard to tell whether it was due to ice interaction or not. However you said the ash was very coarse and rough, while eyafjallajokull ash was like powder, so maybe that is an indication, and could mean the glacier actually didn’t have much to do with the eruption at all .

Tarawera was insane, it was even more intense than grimsvotn, 2 km3 of lava in less than a day, a record for basaltic eruptions in recorded history, and its warning time would make even hekla jealous. While 6 hours is a lot more than 30 minutes, hekla even then was pretty notorious for its lack of warning which ironically became its own warning. Tarawera is a really weird volcano, it is a mass of lava domes which formed in the 1300s, it is also made of rhyolite, and it was the first holocene eruption within the okataina caldera. The 1300s eruption there was a VEI 6 rhyolitic plinian eruption about as big as pinatubo, followed by years of large scale effusive dome growth, similar to chaiten now but a lot bigger, all of this takes a long time. It is also in the taupo volcanic zone which is a forming silicic LIP that is 90% rhyolite and characterised by having the biggest number of currently active large calderas in a single area anywhere on earth.
There is literally nothing about that areas entire history that would lead anyone on 9 June 1886 to expect an explosive basaltic eruption would start early the next day. The most interesting thing though is that the amount of basalt in the taupo province is so small over the timescales involved in its creation that there seriously could have been more VEI 8s there than eruptions like 1886…

I wants to visit Mount Erebus
Mount Erebus is a volcano I wants to visit..
Thats the only volcano in the world .. that haves a high viscosity lava lake about 100 times stiffer than Hawaiis lavas. That alkaline evolved phonolite lava lake is the strangest stuff I can ever imagine in my head.
That lava lake behaves completely diffrent from the more fluid basalt lakes.
Erebus is proof that even more viscous magmas can have lava lakes under correct conditions.
Petrologicaly that volcano is intresting too.. with similar compostions as Kilimanjaro.
Erebus is anorthoclase tephritic phonolite and phonolite with huge crystals in the groundmass
Erebus magma rocks seems sometimes to have green light grey tone .. or even dark green – grey.
Alkaline Continetal Rift volcanoes in the west antartic rift system.

Visiting Erebus rim coud be dangerous as that stiff lava lake sometimes explodes with gas slug slow.
I seen enromous phonolite spatter bombs thrown on the rim in old photographs etc… scary
Despite being souch a cold cruel place, I wants to visit Erebus

I agree that there must be a certain ascent rate above which the descompression must be fast enough to fragmentate even basalt to ash but if Tarawera or Grimsvotn were above that rate I am not so sure because after all Lake Rotomahana was pierced by the fissure of Tarawera so… Do we know if that might have taken a part in the explosivity?

I think the first part of the tarawera eruption happened on the top of the mountain itself and that was explosive too so the lake probably didn’t have much to do with that. I imagine the eruption as being like some of etnas really huge lava fountains except on a long fissure, there are no mentions of any significant lava flows so the lava must have been thrown really high to land as a solid. There were probably some small lava flows but nothing that made it beyond the vent area.

In the recent news, a scientific paper from the Cadiz university speaks about Tenerife and Gean Canaria getting closer by 1mm/year (at the moment at least).

This doesn’t sound crazy – the Canaries are a collection volcanoes sitting on a very complex faults system, and some movement is very much expected.

What I don’t get, however, is the fact that the scientists APPARENTLY imply that the two islands could collide within a few million years. I say apparently since the paper is paywalled as usual, so I can only rely on the paper’s abstract and second-hand info.

The abstract itself only mentions “movement of Tenerife towards Gran Canaria that should be studied in the context of the entire Canary Islands archipelago”. However, the article from phys.org does quotes the professor University of Seville teacher Cristina Torrecillas stating that it would take a while for the collision to happen.

This phenomenon is apparently related to Tenerife sinking on its own weight, some pressure readjustments, and some ‘residual plate velocity’. I copied the links below.

Now, the Canary islands wobbling about is something to be expected. And there is regular seismic activity right in the middle between the two islands. But how could the islands actually get closer to each other to the point of colliding, without plate subduction? 64km isn’t a huge distance, but I have a hard time to imagine this distance being compressed to zero just because of cracks readjustments and volcanoes sinking. It’s a lot of rock to compress hide under the crusty carpet.

Have been trekking around Tejde and other volcanoes closeby for 10 days now and gazed over to the other islands but not seen any change. 😊. Wonder if Gomera and La Palma will be sucked into the pit if Tenerife goes down?

In 2013 I hiked atop Oraefajokull, craziest hike ever, 12 hour up, 5 hours down, most of them on relentless steep ice cap. You can’t do it without professional gear.

From the top, I could see all Vatnajokull volcanoes and Katla. Spectacular but there are other equally rewarding volcanic views in Iceland.

Hiking Kerlingarfjoll allowed me an even better view: I could see literally almost all volcanoes from there except for Westman Islands and anything north of Askja or south of Hengill. I did this after Grimsvotn eruption so I could see the dark spot in Vatnajokull in the distance.

An also impressive wideview is seen from Hekla but you risk life for it. Takes 7 hours in total.

Myrdalsjokull is too dangerous to hike, but I was there, at its edge. Easiest at Fimmvorduhals, which is still a risky hike. Oh and it takes 12 hours. Same if you hike Eyjafjallajokull (which shouldn’t be attempted unless you’re professional)

Kerlingarfjoll is actually the easiest of all of them and the best view. Still a steep hike but doable for most hikers. About 4-5 hours only.

Other touristic options include hiking inside Askja and Krafla. Less than 2 hours.

Eldgja is a easy 2 hour hike. But driving there requires fording 10+ rivers on a jeep. You can take a bus tour.

Great tips! I will try Kerlingafjoll if weather and time allows next time I go to Iceland. My only hike near a volcano on Iceland was a guided 7hours glacier trekk on Fimmvorduhals. The black ashlayers there from Eyjafjalla eruption and an earthquake during our trekk was the trigger for my volcano interest.

After reading trough the paper it doesn’t reach any really interesting or unexpected conclusions. It measures ground movement across several points of the island respect to the movement of the Nubian Plate (which is about 16 mm/year) and is what they refer to as the residual velocity and is of about 1-2 mm in the different stations, the research identifies two main deformation trends trough the island, subsidence and compression of the central part which is interpreted as isostatic adjustment of the Teide Volcanic Complex and extension in the Anaga Massif, and they propose this may have something to do with a submarine fault. I don’t recall having seen any mention to Tenerife and Gran Canaria getting closer anywhere, only that apparently Gran Canaria has a different behaviour in terms of the deformation to Tenreife and this should be studied for any possible relations to crustal flexure or the faults active between the islands (I guess they refer to the very common swarms right between Tenerife and Gran Canaria).

Now what I have read doesn’t match at all with what the news say. I think that the daily mail article is another case of ill-informed periodism, they have mixed different bits of the research in a wrong way (relating Anaga or the 2004 unrest to the subsidence…), and they make other parts up like the “volcanic blasts”, or the two islands crashing against each other, I am still trying to figure out from where might they have came up with it.

Apparently it all comes from a professor who basically said it would take a very long time for the Islands to collide. I suspect the sentence was taken out of context – she probably didn’t meant at all that it would actually happen, and simply implied that we are talking about very minute movements.

Now I wasn’t under the desk during the interview – maybe she did screw up.

Ironically, the professor’s sentence in the article cannot be copy-pasted from the website for copyright reasons 😀 I wonder if the authors of the actual paper have any idea on how it was turned into a sort of Hollywoodian scenario ^^’

Makes perfect sense, if you give periodists something to make up some kind of apocaliptic scenario out of they will. If that was what happened then the authors are going to be really surprised when they find about all of this mess.

The quakes between Tenerife and G.C. are because there is an active volcano there (28º05′24”N y 16º10′1.4”W). It’s called “Volcán de Enmedio” (“en medio”, as two words, in Spanish means “mid way”… so it translates as “Mid-Way Volcano”). Of course, it’s underwated: it tops at about 1630m under the sea level.

Not looking good at all. Pacific Coast Highway has been designated as the evac route, but reportedly it is closed at Topanga canyon. It was noted as being zero percent contained.

Reportedly, if a fire crew arrives and finds a structure at 25% involved, they will skip it and proceed to protect lesser involved structures. Their crews are stretched that thin.

Beating a dead horse here, but this is why you do controlled burns. That clears low level ground clutter when conditions are much easier to control. That way when conditions get like this, you don’t get as high a runaway fire threat. I don’t see much in the live videos that appears to be “Crown Fires” but when crown fires occur, they literally sterilize the ground and make foliage regrowth very very slow to occur. Loose foliage, and the risk of landslide goes up when the rainy seasons kick in. Sorry for the deviation in topic, but it ticks me off that something preventable was allowed to get to this condition.

Reportedly, relative humidity is in the single digit realm with 5 to 33 kph winds.

Reporters are musing over whether the Pacific Coast Highway will serve as a fire-break or if it will jump the 4 lane highway.

One Aircraft-11,000 * US gallons. Gravity Feed tank. Douglas product
whats not to like..
I like the DC-!0 Tanker idea better than the 747 ‘super tanker.”
1. the gravity feed tank has better dispersal tha a pressurized system
2. As it is flown the ’10 is actually a bit over powered not a concept I can understand
from my DC6/& days. We were at Paso Robles talking to a couple of S-2 (800 gallon piston engines at that time) Us.(DC7) “What about those high tension wireds off the end of the runway?” S-2 drivers:”what high tension lines?”…
3. the ’10 can oerate in tighter spaces than the 747. both on the gound and in canyons. Not to say the 747 doesn’t have its place, just different tools.
BTW Santa Anas are no fun to fight on the ground or air..

S2F or “Stoof’. Calfire rebuilt a bunch of those over th eyears hung turbines on then with 1200gallon tanks. great little initial attack
aircraft…
Oregon uses the Single Engine Airtanker (SEAT) In the same fashion. If I can get rid of some of these nagging issues with my health (Skeletal Muscular) i do do that again..
finally found a physical therapist that is doing some good..

Heh… Reporter interviewing a local who has lived there for decades and been through many fires, what asked about what he thought, stated the likely path it will take and that it will come out next to the reporters truck.

For those who don’t know, the Santa Ana winds are going to make things really really rough/dangerous there this evening.

Fissure 8 looking down the channel, the cone is about 50 meters high above the pre-eruption terrain (luana street), and probably 350-400 meters wide.

420 meter wide lava channel, assuming it as a cylinder shape 12 meters deep and 420 meters wide it contained 1.6 million m3 of lava at any one time, which is equivalent to 2-5 days of pu’u o’o eruption. In reality it isnt even close to round and is a lot longer so the number is probably a lot more, the channel could have contained over 10 million m3 of lava at any time and in June there was a mention of the lava taking about 2 hours to flow the 13 km from the vent to kapoho…

Final picture, fissure 22, a nice neat cinder cone, probably one of the best examples of a cinder cone you will ever see even if it isnt a towering mountain like paricutin.

Also a 3D simulation of pu’u o’o. The crater is a deep cylinder shaped pit, 300 x 320 meters, it probably has a volume of around 22 million m3. Assuming the initial dike had a height of about 3 km and width of 3 meters, and a length of 26 km, it would contain 0.23 km3 of magma, so clearly there must have been way more stored in the rift, and even more in the summit because the rift never collapsed, meaning the magma was all replaced.

My reasoning for the dike being so big is that the big quake would have moved the flank outward, not much at the surface but at depth probably by a fair bit, so the dike is probably quite large. It would also need to be pretty big to contain the volume of magma being erupted, which was very high.

I dont know how wide the Pu’u’o’o dike might have been but I remember we were discussing how could the summit collapse have matched so good the volume of the eruption when it should have been bigger. I think that the east rift put all of the intruded volume, looking at the InSAR pictures it seems like the summit didn’t really start deflating markedly until at least may 8, and the first fissures had already opened 5 days earlier which means that practically all of the volume of the intrusion came from the ERZ most specifically I would say it came from shallow fresh dikes in the Pu’u’o’o area, also the Leilani dike wasn’t so long since it started from Pu’u’o’o also explaining why the collapse volume matches so well with the erupted one.

A lot of the initial deformation was uprift of pu’u o’o, around mauna ulu and makaopuhi. Basically all of the east rift between mauna ulu and heiheiahulu deflated in the first weeks of the eruption though, while the area beyond the highway inflated a lot. The fact there was deflation this far probably means there was already magma there, and several eruptions in the 1960s and 1977 did erupt from fissures that extended beyond pu’u o’o basically the entire length of the rift between makaopuhi and heiheiahulu. Pu’u o’o formed in the middle of this, so maybe it shouldnt have been surprising that it lasted so long when the east rift was so active in this area 15 years earlier. This also could have been the area of magma storage that was created during the 1975 quake.

What is notable is that there was no deflation on the large scale between mauna ulu and keanakako’i, the upper east rift where it supposedly takes a path that goes against the trend of deformation. This indicates there is no shallow magma under this area, so the east rift must be being fed from fairly deep down, or through the koae fault system, or both. There was also no deflation on the southwest rift, so there probably isnt any shallow magma there either. This basically means the summit and east rift are almost separated now, which could be indicative of a very imminent relocation of the main eruptive center to a more southerly position than it is now.

There was also some discussion about the recent DI events at the summit being from the south caldera chamber, and with each event being a lot bigger than it looks because of the depth. The halemaumau reservoir was at less than 1 km deep, and it caused changes of about 5 microradians, the south caldera chamber is 4 times deeper, so an equivalent detection would be 4 times as big in reality. Halemaumau is also twice as close to uwekahuna as the south caldera chamber is too, which rounds the numbers up even more. What this means is not really obvious yet but the most recent DI event could have been a quite big drain of magma to the east rift.

I measured the thickness of the flow with the new point clouds they released during the eruption by comparing it to the pre-eruption topography in two different parts of the main channel and the surface of the lava in both was 16 m above the pre-eruption ground and since at that time it wasn’t overflowing, during a surge the level of the lava would have been 2-4 m higher..

Very wide perched channels are probably a good indicator of really high effusion rates in very fluid lavas. The perched channel of the 1974 SWRZ eruption of Kilauea is about 100-200 m wide and emplaced in steeper slopes than usual so likely very fast-flowing. There was one of this channels in Alayta that was even wider than fissure 8’s with up to 600 m wide (though it may have ponded a litlle in that part), In Iceland these features are also present but difficult to distinguish with all the rivers, ice, erosion… The Krafla Fires produced a perched channel that at some points it almost reaches 400 m wide and I also managed to locate one that was feeded by some of the Laki vents and it is mostly 100-200 m wide:

I got it from the ArcticDEM explorer. ArtcticDEM has elevation data of very good resolution though sometimes datasets with errors or missing parts and encompasses a very wide area around the arctic, Iceland, Kamchatka, Alaska and their volcanoes fall within its coverage.

Its still glowing inside… lava is an amazing insulator
I remeber they cut open roads in the 2012 Puu Oo lava flows recently .. and it was bright red rubble
Leilani 2018 will stay hot for many many years in the thicker parts
Even Pahoa flows of June 27 have not cooled yet still steaming after rains
Low heat conductivity

It was red from iron oxide not incandescence, it is a good insulator but not that good. The 61 g flow was glowing at night for about a month after it stopped flowing. The peace day flow probably glowed for a similar length of time. Some of the older flows glowed for longer as the lava eruption rate was often higher in the 1990s-2000s than it was recently.
The inside of the fissure 8 flow will very likely still be glowing though, especially the lava delta where some of the new lava is 300 meters thick offshore of where ahalanui was. If a big bench collapse happens there it will probably cause a huge explosion.

its a very good insulator… Kilaueas ikis deep rootless lava lake is still very very very hot at bottom … likley around 390 c at hottest 2018
Being souch a thick cooling unit… it will form amazing columnar joints

“A Giant Sun Storm During the Vietnam War Likely Exploded Dozens of Mines
“The extreme space weather events of early August 1972 had significant impact on the US Navy, which have not been widely reported.” ”

From the reference paper: “The energetic particle bombardment created a Northern Hemisphere polar ozone cavity—a 46% reduction at 50 km that recovered over several days; while at ~39 km the ozone cavity persisted and circulated as a semirigid structure for more than 50 days”

I have seen a few comments up above about unusual signals at Haukadalur SIL-station (seismometer).
That particular station is very noisy indeed even at the best of times, with loads of weird signals.
The reasons for this is both natural and man made.
None of it though has anything to do with Hekla in and of itself.
Relatively near Haukadalur is a lake called Illuvatn, at the bottom are geothermal wells causing a lot of “wet” signals. Illuvatn is an old eroded low laying crater, a remnant of volcanism in the distant past and not an active system as such, and not at all related to Hekla in regards of composition.
Next thing is man made noise, and there’s a lot of it. Mainly produced by local farmers who enjoy driving their tractors to the spot of the SIL, where they can sit and talk while idling their engines and listen to Icelandic dubstep on over sized boom-boxes.

In short, to find any relevant signal for Hekla on that station (not counting during eruptions) you need to be a level 50 magician specializing in divination hitting a perfect score with your dices, and still you need a benevolent Game Master accepting your level of crazy. 🙂

Just disregard this station and go for MJO and FED instead, they are more fruitful for serious divination.

Is this correct?
Grimsvötn maybe a trapdoor caldera when it comes to eruption mecanism.
Just like Sierra Negra. Magma accumulate in grimsvötns upper magma chamber, thats a flat massive sill laccolith form thats feed by an open conduit. As the magma chamber expands.. it expands and cracks the sorrounding rocks causing earthquakes. It also inflates the caldera
When the pressure gets high enough .. the magma goes through the ring faults in sourthen caldera and erupts. 1998 , 2004 and 2011 occured very close to eachother, maybe a more permanent eruptive ventile is forming there.

But if it is like that… there should be lots of earthquakes around the faults in the caldera floor slab over the expanding magma chamber in Grimsvötn. Thats what we are not seeing before a grimsvötn eruption.
Grimsvötns magma system is quite poory mapped I think.

It has now been 66 days since lava was last at the surface at Kilauea. That is the longest gap since the start of the eruption in 1983- there were 65 days between Episode 2 and 3- and the longest since the 4 months between the two 1982 eruptions. And with no signs of imminent renewal, it seems very likely that the current gap will reach the 90 day mark on December 5- which means the eruptive period that started in 1983 has come to end. When eruptive activity does eventually return, it will be an entirely new eruption.

I think HVO is considering the Leilani eruption as a separate event already, even though it was a flow on event from pu’u o’o. I think it is because the magma was ultimately different to pu’u o’o, a bit more primitive and it also had effects much wider than pu’u o’o. The 1997, 2007 and 2011 eruptions uprift of pu’u o’o are also considered separate events because their magma was different. The 1973 eruption near mauna ulu is also considered separate from mauna ulu even though there was no pause in eruption then.
I think the overlook crater was also considered separate but I don’t know because it doesn’t exist anymore.

It is also important to consider that if an eruption begins on the rift near heiheiahulu, or in Leilani again, it would be a direct result of magma gaining access to that area this year. In a way though I guess that means every eruption since 1955 on the east rift is a follow on event of the last one.

True, but I go with the GVP rules that an eruptive period is for any activity regardless of vent location(s), so all events from 1983 till September including the LERZ and summit are regarded as one event, and the rule that a new eruptive period begins after at least a 3 month pause, and that’s even if unrest doesn’t stop completely, like at Sakurajima (1955-2016, 2017-now). Or even if the gap is literally 92 days instead of 91. So arbitrary but generally useful.

In other words, when lava is present at the surface full stop (Masaya has been “erupting” since 2015 even though all lava has stayed within the lava lake for example), with the exception of entirely phreatic sequences, in which case the 3 month rule is between explosions instead of if lava is present at the surface.

Besides, of course, in the 3 days between Pu’u O’o’s crater collapsing and the opening of Fissure 1, the lava lake was still there so there was no pause at all at that point. And yoiu have to consider that we are somewhat-uncharted territory here, so things could and I’m sure will end up being reconsidered, as the idea of the mechanism behind the 1924 summit explosions was.

And then on top of individual eruptive periods, there’s eruptive “eras” I suppose. Like Mt St Helens 1800-57 and 1980-2008, or indeed at the ERZ since 1955, or Kilauea in general in the current effusive-dominant cycle, or since the end of the long hiatus in 1952, or really anything. These deal with longer-term trends, which I suppose is more useful.

So Kilauea can still be considered to be in a phase of very high activity (as is Sakurajima, or other examples of recently-ended-long-term-periods-but-still-regularly-erupting volcanoes like Semeru and, just yesterday Sheveluch (1999-2018, 2018-present- its last explosion was in January)) even if Kilauea changes back to short but frequent eruptive periods, which I think it will- I’m “predicting” the next eruption will be a fairly brief (less than 1 year) one starting in about the middle of next year. Then if a phase of more spaced-out intermittent eruptions happens, like between 1975 and 1982, then that could be a particular era.

Oh and I should note that I copied my comment from the update I did for Volcano Discovery- so of course not necessarily official but I try to keep some degree of consistency since I’m dealing with activity globally, so this keeps it simple.

In any case, obviously the LERZ eruption stands out on its own, as with any major developments like at Erta Ale in early 2017, so it is for the most point just conjecture- certainly the residents won’t give much of a crap! The general public sees it in black and white- a volcano is either erupting in my backyard right now or it isn’t! 😀

Also, however you divide the recent events, we can still say we are in the post-Pu’u O’o world!

End of long-winded answer- I think it’s rubbing off on me from someone else who likes to post them, no idea who it might be!!! 😛

Oh one last thing, I wonder if Kilauea will, even briefly, end up being lowered to Green/Normal before the next eruption starts….. Now that would certainly have been unimaginable as recently as early March this year! I suppose it depends if you could call the current level of activity “normal, background”, assuming it stays at this level into the new year or however long HVO would want to wait before declaring dormancy if it comes to that. If! For now, we can let the residents enjoy the rest-bite from vog!

Interesting, I didn’t know there was an actual cut off point, but I guess that makes sense. That would though make the 1959 and 1960 eruptions a single eruption, as there was only a bit over 2 weeks between the last fountain at kilauea iki and the fissure opening at kapoho.

One thing I did notice on both the volcano discovery page for kilauea, as well as your comment directly, is the idea that kilauea is either explosive or effusive. It is both at the same time. The so called explosive period of 1790 was actually a single big event in that year, and during the entire 17-18 centuries there were frequent eruptions on the east rift, some of them were very large like the ~1790 eruptions which erupted at least 0.5 km3 of lava. There was also the eruptions of pu’u honuaula and kapoho crater, which were at least as big as 1960 with pu’u honuaula being probably comparable to this year. The biggest if all was the probably decades long heiheiahulu eruption, which was similar to pu’u o’o and probably erupted about 2-5 km3 of lava, about half of pu’u o’o. The interesting bit is that this eruptive period lasted over 150 years, the current period has lasted only 70 years, but the current volume of the ongoing episode is much higher.
I have recently been thinking about my theory, maybe the best analogue for this years event would actually be the pu’u honuaula eruption, the cone which formerly had the LERZ webcam on it. That cone is about 60 meters tall, impressive compared to the other cones around it which are much smaller. Fissure 8 is comparable in size which means it probably had a similar formation. Pu’u honuaula is poorly dated but it formed anywhere between 1650 and 1750, it was probably in the latter period though. My idea is that this eruption might have induced a summit collapse which ended without significant activity there, and also lowered the magma column to that level. Some years later another eruption occurred at kapoho crater and because there wasn’t as much gravitational draining it wasn’t as voluminous but did create a big cone through water interaction. Later still there was the eruption that created heiheiahulu, which occurred at the point where the base magma supply was able to reach continuously along the existing conduit, curiously this is also where recent deformation has been happening. This probably stayed open for a long time, but as the shield grew taller it became favourable for a dike to form downrift, possibly this happened twice with a time gap before the conduit was collapsed entirely with pit crater formation and caldera collapse. The return of magma happened with a big rush, which was the 1790 explosive eruption.

To summarise, the idea is that periods of explosive activity at the summit are occurring when most magma is erupting on the east rift as it is now. Currently we are in one of the ‘explosive’periods because no lava has overflowed the caldera in 700 years and only tephra has escaped, even though most activity is effusive. My idea also has implications that the current episode is still far from over despite its already very large volume. Perhaps the larger volume is indicative of future large scale summit activity, or a summit relocation to a point further south than it is now, or both.

The idea is that the explosive eruptions correlate with reduced feed from depth, but that doesn’t seem to be the case when I have poked into it further. Really the only thing which actually seems to put Kilauea into a state of lower activity is the more infrequent occasions when mauna loa becomes more active. Mauna loas most recent period of activity was between 1840 and 1950, it has only erupted twice since then, but it also erupted infrequently before that too, its previous period of high activity seems to have been over 400 years ago. The fact Kilauea had a major eruption just beforehand probably added to this but other large events comparable to 1840 (like 1960, or this year) which occurred when mauna loa was not active have not lead to such a reduction in activity.

The effusive-explosive cycles model of HVO refers to periods of low supply when a caldera forms in the summit and explosive eruptions take place (the explosive period), and periods when the supply is high and effusive eruptions take place. The problem is in the method they have used to select the periods during which more volume of lava was erupted in a effusive way. The thing is that they use the summit overflows as representative of all effusive activity of the volcano, so they are leaving behind two kinds of effusive activity: caldera filling and ERZ eruptions. Practically all of the dated flows in the volcano come from flows that managed to overflow the Kilauea Caldera and spill over the south and north flanks, the ERZ is very poorly dated and past caldera filling is usually invisible: happens within a relatively small area that is later buried or collapses again… But both have a very significant volume, I think the volume of caldera filling during the historic period was of around 5.5 km³, and the volume erupted from the ERZ likely is even more than that. The historic period has been considered effusive because we were there to see it and we know it was but for the prehistoric period HVO has used the 200 BC Kipuka Nene flows and the 1000-1500 Observatory Shield, these two are the periods when there was no caldera because it was filled and flows from the summit flowed down the flanks covering wide areas in extensive pahoehoe fields. This has several problems one is that it ignores ERZ and caldera filling and there is reason to think that these two do not happen at the same time as summit overflows. For the caldera filling I think it is obvious and for ERZ activity during the historic period it has been observed that 1823-1955 was basically a period of summit eruptions and then 1955-present went into the east rift so evidence for more of a cycle (summit-ERZ) than (high supply and effusive activity-low supply with caldera and goes explosive). With the methods used in the explosive-effusive model the historic period would also fall within an explosive low supply period, why? because they would have looked in the south and east from the summit areas, found no flows there, most of the 1790-1955 caldera filling would have disappeared into a new caldera or would have been buried by a summit shield and the ERZ would be poorly dated and underrepresented, so they would get a gap with just a few dated flows between 1500 and 2200 (lets say) which would coincide with some explosive events and then assume a low supply and not much effusive activity for all of that period.

Instead of effusive-explosive cycles Kilauea would be always effusive and have some punctual explosive events. Instead there are likely summit-ERZ cycles and Kilauea-Mauna Loa cycles which might actually be part of the same as the transition in Kilauea from summit to ERZ occurred more or less at the same time as Mauna Loa went for a nap. 1950 was the year when the frequent eruptions of Mauna Loa ended and when a voluminous ERZ intrusion caused signigficant deflation of the summit of Kilauea (breaking a period of dormancy there), and by 1960 the ERZ was erupting almost every year.

Heiheiahulu, Puu Honualua, Kapoho Crater, the Kahawali flows maybe Halekamahina… all of those LERZ eruptions likely happened sometime between 1500 and 1790 but it is harder to say if all of those belong to one period of ERZ activity or if there was some kind of return to the summit in between. I think the biggest collapse was triggered by the 490 BP flows, based on our summit-ERZ model then 490 BP would have first opened the rift zone after 700 years of summit activity, it probably was also responsible for the Puulena explosive eruption in the middle LERZ and may have inspired the Pele-Hiiaka legend and also destroyed Puna and may have even killed some natives, as it was likely unexpected, it may have included explosions had a really long fissure and was likely a fast one. Or there was some ERZ activity preceeding the 490 BP flows hard to know, this last is mostly speculation and I don’t have much time now to go deep into this and the eruption is not well studied anyways and now mostly buried between the Puu Honualua, 1790 and 2018 flows..

The one biggest reason I have for going against the main accepted idea is that the explosive eruptions are mostly magmatic, it takes a full blown lake (and hence a very deep full sized caldera) to turn a lava fountain like 1959 into a phreatomagmatic eruption, wet ground is not going to do anything except dry out in the intense heat, which means most of the explosive eruptions on kilauea, and many other basaltic volcanoes, are not caused by water interaction but by a large amount of magma erupting quickly. On kilauea this is mostly through the summit but evidently it is possible for the east rift to erupt that way too (alae crater, pu’u lena/pawai/kahawai craters and kapoho crater). Of all the explosive events, only kapoho crater and the 1790 event have good reason to be assumed to have been phreatomagmatic, kapoho crater because of location and 1790 because of observation and records of a lake. However a lot of the older tephras are lava fountain fallout or completely dry and indicative of being erupted in the absence of water.
All of this means the explosive eruptions must have not only been very powerful by historical standards (VEI 4 or 5) but also involved large volumes of magma ascending fast enough to avoid degassing, which is very similar to tarawera which I mentioned earlier. This doesnt sound like a volcano in low supply, especially if this is also occurring while rift activity is high.

This also makes the risk of the next eruption now being pretty big and violent quite high, there is evidently no shallow magma anywhere with the low SO2 emissions so there is no way to degas the system, so the next eruption will probably be quite intense, whether it is at the summit or not. This years eruption will have basically cleared out any magma that is older than a few months from the system, so the whole of kilauea is now primed with fresh magma that is evidently still in high volume. The south caldera chamber is the same as before, as is the east rift which extends from it at a pretty constant depth, only the upper magma chamber (source 1) which was under halemaumau, and while that is probably gone it was only the smallest part of the magma system at the summit, with maybe 1 km3 of magma which is a bit less than the volume removed, the south caldera chamber probably contains at least 3 km3, which added to the amount in the east rift (probably a bit over 1 km3) and the deeper source 3 which probably contains even more but is usually to deep to drain through gravity. There is probably about 6 km3 of eruptible magma within kilauea, and maybe a lot more if the deep rift is a thing and there is magma all the way to the base of the rift fault. It is very unlikely that this will ever all erupt in one go but it does show that the potential for eruptions like this year happening again is there and might be more likely now than at other times before.

People who wrote things down were exploring the pacific ocean many hundreds of years before the first actual Western contact of Hawaii, if the Spanish or Portuguese explorers in the 1400s found Hawaii it would have created a very different idea of the volcanoes there now. If the Chinese explorers in the first millenium AD found it then they would have seen Kilauea at its most violent in thousands of years, when most of its larger eruptions were bona fide plinian events.
Hypothetically if anyone found it during the ice age 20,000 years ago then it would have been seen as a snowy and very explosive volcano, an image that better describes a volcano in Alaska than Hawaii today. Someone in 20,000 more years will probably describe kilauea as a place where lava never ends, where eruptions are continuous and events as big as this year happen every decade or so. Someone in 100,000 years will probably look at kilauea as the biggest mountain on this earth – a snowy, (and possibly glaciated) monolith that is over 100 km wide and 4-5 km above sea level, like mauna loa now.

I am not convinced by that. (Also note that VEI 5 is a ‘small’ eruption!). Kilauea gets its magma from a conduit that makes use of the faults on the south side of the big island. Mauna Loa’s bulk causes movement and fractures along the steep south side of the island, roughly parallel to the Maun Loa rift zone itself. Kilauea acts as the focal point of that system, and from there magma is redistributed through the various associated rift zones. But you can already see that the rift zone runs well south of Kilauea. As Kilauea grows, it pushes the faults southwards. In a way, it stabilizes the area where it is. If it grows much taller, there is a risk that it cuts off its own magma supply by closing the relevant fault. It already exists in competition with Mauna Loa. If it gets much bigger, the feeding fault goes further south and the magma below the island no longer has an easy path to Kilauea and more will end up going towards Mauna Loa. Kilauea could be a victim of its own success. Of course this is guessing. But magma can easily be led astray: you have to be careful with your conduit.

VEI 5 is not a small eruption when it is a result of a surge of basalt into a low pressure environment. Basaltic plinian eruptions are only superficially similar to silicic plinian eruptions, the basaltic events are basically lava fountains taken to the next level and as such would be way hotter and contain much more energy than a rhyolitic plinian eruption of the same magnitude. Rhyolite is generally at about 700 C when it is erupted explosively and maybe 900 at most, kilauea has historically erupted basalt in the range of 1200 C and the magma is probably close to 1500 C at the base of the mountain so it is twice as hot.

Also kilaueas magma supply is way too high to be contained in the manner you describe, the sources for both volcanoes are very deep over 50 km, and around the same distance away from each other. The structures within both volcanoes are 15 km deep at most. kilauea is not going to strangle itself, it will just relocate the center of eruptive activity to be in line with the east rift more, or the east rift will be redirected further north through kilauea iki (probably the first option with the way things seem to be going) and continue as though nothing happened. Currently the east rift seems to be fed from depth too at least at its upper reaches, there is no shallow magma under the area between hi’iaka crater and the caldera which means there is no supposed shallow connection.

And yes both of the volcanoes are competing but kilauea is easily winning that competition, 3/4 of the past 1000 years kilauea has been dominant of the hotspot, it appears different because historical time coincidentally lined up with a period when mauna loa took over and kilauea was quiet. In the past 200 years the two volcanoes are indeed comparable, but in the past 10,000 years or so kilauea has definitely been growing much much faster. In another 10,000 years it will be even more obvious, and mauna loa will have likely gone into its post shield stage by 20,000 years. These are all seemingly big changes but they are not as drawn out or gradual as you think and the transition of dominance to kilauea is already well underway and proceeding fast, only 15,000 years ago kilauea was half its current height and its caldera was big and basically at sea level, making nearly all of its eruptions explosive, this is what created the Pahala ash. Mauna loa has barely changed in overall appearance since then, except that it was glaciated in the ice age.

Also in 20,000 years loihi will still be too far from the center of the hotspot to compete with kilauea, it will probably stay below sea level until about 50,000 years in the future and then go through the same procedure as kilauea now.

Yes, the part of the low supply during explosive periods is not convincing at all. If the supply is low the volcano doesn’t really do any intrusions or eruptions so a caldera will not form to begin with. The theory where Aila’au is responsible for the caldera collapse is based on that the eruption somehow kept going for decades even with a low supply rate so that the magma wasn’t being replaced and drained away to form the caldera around 1500. But this kind of eruptions happen with a sustained supply and if the supply would drop the volcano goes quiet, like Mauna Loa recently (though maybe after 34 years it might have been able to build up enough magma to erupt again).

Puulena was probably phreatomagmatic as many other explosive eruptions of Kilauea must have been.

The Chinese would have need to be really lucky (or unlucky) to see Kilauea during its violent explosive eruptions of 600-900 AD because the full Kulanaokuaiki Tephra migth actually have just been 2 or 3 events, the lower Kulanaokuaiki Tephra maybe 2 explosive eruptions happening around 600-700 AD and then the Upper Kulanaokuaiki Tephra maybe a single explosive eruption which was the biggest one somewhere between 700 and 900 AD. There was erosion between the upper and lower units so at least those two are different events and if I recall correctly one of the layers of the lower part had a very distinct composition. But then just 3 events that maybe had a few hours of paroxysm and then maybe days of weaker activity? but no more than that.

Didn’t the Pahala ash came from subglacial eruptions at Mauna Loa? I don’t think it has ever been clear which of the two was the one responsible but I find the Mauna Loa version more likely.

There is no shallow magma between Hiiaka and the caldera at less than 1 km depth but it might be at 3 km depth and I think that is what you still consider shallow. At that depth it doesn’t degass SO2 and a reservoir there wouldn’t have collapsed during past summer eruption, the only two collapses happened from very shallow magma bodies, less than 1 km deep? in fact both were in direct contact with the surface through the lava lakes at Halema’uma’u and Pu’u’o’o, the South Caldera Reservoir is still intact as are any magma bodies in the UERZ. And I don’t think there is such a source 3 either.

If the connection between the ERZ and the summit was lost because of the rift zone shifting too far south then Mauna Loa would likely become dominant again, dominant there actually means shared because in dominant periods of Kilauea almost all supply goes into it but during periods of dominance of Mauna Loa this last one still shares enough with Kilauea to maintain a more or less sustained activity there. The last true dominant period of Mauna Loa might have been around 0-500 AD when as far as I know Kilauea didn’t do anything and Mauna Loa… well, Mauna Loa did Panaewa. I don’t have and estimate of the volume of that eruption but seems to have been really big, maybe bigger than any other less than a year long eruption of Mauna Loa since then. But even if the ERZ would shift too far south (something which isn’t really known for sure to be happening, and the summit also seems to be mobile to a certain point and shifting south too) I guess the hot spot would eventually get too far away from Mauna Loa to feed it and it would mostly go to Kilauea again. I am guessing though that the ERZ initially formed as a radial feature of Kilauea and then shifted south to the point that its current location makes it difficult for magma transport between the two (it has to get trough that gap with almost no eruptive activity between the caldera and Mauna Ulu) the rift zones are known to be dynamic and the evolution of the ERZ might have affected the activity of Mauna Loa and Kilauea and will keep affecting them, but the one moving south now seems to be the summit while the ERZ seems more or less stable at its location. Don’t know if that trend will continue.

Source 3 is generally non eruptive, it is also not exactly a magma chamber but more a term to describe the complex feeder that extends to the mantle source. It also probably extends within the rifts somewhat too, it still contains a lot of magma, probably more than the rest of the system, but it only erupts on rare occasions like 1959 or probably 1840. 1924 is known to have induced wide deflation of the entire volcano, which indicates that it involved deeper parts of the volcano.

I dont think that the east rift becoming inactive would directly cause mauna loa to erupt more, the east rift was entirely inactive for most of the 50 years before 1840 and mauna loa didn’t erupt at all. In the last 1500 years mauna loa has been relatively inactive though, it is hard to know anything about kilauea older than that because it resurfaces so quickly but I think it is safe to assume it was probably not too different. There was a period in the early Holocene where mauna loa was apparently almost totally inactive for over 2000 years based on the presence of coral reefs that are now buried.

Last time I read, the Pahala ash was from kilauea, there are extensive beds of it on the south coast of kilauea below hilina pali, some of them look almost like ignimbrite layers. The parts exposed on mauna loa are not as thick. It would also make more sense for it to be from kilauea as the wind blows from that direction.

Kilauea may be able to erupt superheated basalts
Hawaii is the worlds hottest oceanic hotpot
Its about 1520 C in the hotspot melting zone.
It takes around 8 years for the magma to rise from the hotspot astenopshere to the halemaumau summit crater magma plumbing system and lava lakes. During that time.. it have cooled from 1518 c to around 1213 c as it emerges in halemaumau.

When Kilaueas supply sourge in the future.. the magmas will cool less.
Hawaiian hotspot is growing more powerful in the recent millions years.
I read that some greenland flood basalts emerged at 1400 c when the North Atlantic Magmatic Province plume was at peak power.
It makes all sense that Hawaiian basalts will get superhot as the magma supply sourge and gets faster and magma gets to the surface faster.
In the future Kilauea may be able to do some 1370 c to 1400 C flows
Souch a hot basalt woud be almost ultramafic in temps and superhot

Yes but during 1823-1840 and problably also during 1790-1823 the general trend was of the eruptive rates slowing down, 1840 sped things up but the rates would have eventually lowered below 0.05 km³ with or without it. and it continued to lower until 1950 when shortly after activity in the ERZ started picking up and since then rates have been rising. It is tentative to say then that the rates peaked up towards the end of the past phase of ERZ activity in 1790, and the next 50 years of high rate was just the summit rates stabilizing back. We don’t now if it happened that way or not though Kilauea back then seemed to be very active so maybe. This model where the ERZ regulates the supply to Kilauea and Mauna Loa would also explain some things, mainly why the two volcanoes alternate in activity to begin with, which is not a behaviour widespread in the volcanic world. Magma will take the easiest path out and the ERZ is much more productive than the SWRZ and than Mauna Loa’s rift zones, this probably means spreading is easier there, one reason maybe because one flank of the ERZ is “free” meaning it doesn’t have to displace another large mass to open up. Mauna Loa is party obstaculized by the three surrounding volcanoes and Kilauea’s SWRZ by Mauna Loa and Loihi and the spreading is also shared with Koae. If the ERZ is closed then magma might find it more easier to go get out through Mauna Loa’s rift zones, keeping in mind that the summit of Kilauea is roughly part of the system of fractures of the SWRZ while the ERZ and Koae form a different spreading system farther south. If intrusions manage to create an open path into the ERZ then Mauna Loa gets most of its supply hijacked. We haven’t been observing the two volcanoes long enough to verify these relations but it does certainly explain what has been observed for the historic period. The reason why the ERZ sometimes goes inactive is likely because connection is not easy (the true ERZ doesn’t start right from the summit but until Mauna Ulu, in between there is a gap in eruptive activity with some but few exceptions). If the conduit of Kilauea would rise under the ERZ then Mauna Loa would probably already be in its post-shield stage.

As I said earlier though both volcanoes are pretty far apart in reality, they only look lose because they are gigantic. They are also both fed by entirely different and very deep sources, ranging from 40 to 70 km deep, and the magma is different in chemical composition. Mauna loa is also actually showing a lot of signs of getting to its post shield stage, like eruptions from radial vents becoming common, eruptions not generally covering a large part of the volcano, little if any growth in the past 10,000+ years, and reduction in activity at the distal ends of the rifts, it’s eruption rate averaged is also pitiful compared to kilauea.
The way Albert was describing kilauea is the idea of it basically being almost a flank vent of mauna loa that is only really there for a short time and will self destruct, which is impossible. Kilauea also has much more stored magma in its depths, and a number of it’s eruptions on the east rift already do originate at greater depths than the 3 km magma chamber, 1840 did and 1960 probably also did, but so did 2007 and 2011, and also some of mauna ulu, and 1974, and most definitely 1959, all of which were higher up the rift. I think that most of the rift is much deeper than the summit chambers and at that depth the stresses are probably different, the fact the summit seems to be slowly relocating and that magma is moving up under the southern caldera probably indicates the summit is moving to be above the deep source, leading to increased potential for magma to just start using the koae faults as eruptive vents and completely connect the rift zones.
The tensile strength and pressure resistance of basalt is not anywhere near high enough to force magma which has already risen into kilauea to backflow to mauna loa and erupt at 3 km higher altitude. Basalt that is in the range of incandescence is even worse, and I’m willing to bet that most of kilaueas interior is getting on to dull red incandescence especially if there is eruptible magma being stored there for centuries.

The way I have always pictured the future of Kilauea is with the summit relocating somewhere close to Mauna Ulu, where the chain of craters bends. A rift zone would develop through Koae and connect the ERZ with the Seismic SWRZ through the summit and Mauna Loa would go post-shield. But this is speculation of course, though there is some evidence that this might be taking place with the summit shifting historically southward from the northern caldera to Halema’uma’u and now with the largest reservoir farther south beneath the southern rim then it seems it might continue shifting south. But that trajectory would not be following the Chain of Craters but rather the SWRZ though there always seems to be a secondary summit area, Keanakakoi and Kilauea Iki that might be shifting down the UERZ and the Chain of Craters instead.

Radial eruptions do not necesarily mean post-shield stage, even Kilauea had radial eruptions to the north during the Observatory Shield. Mauna Loa still conserves two very active and well defined rift zones, maybe even more well defined than Kilauea’s which are actually parrallel alignments of fissures, like the Volcanic and Seismic SRWZs and Kamakaia, and same goes for the ERZ. I do agree that Kilauea is currently a more powerfull volcano and not a flank vent and probably driving the spreading of its own rift zones (whatever the predominant mechanism is, gravitational or forcefull intrusions), but in the last 2000 years Mauna Loa has undergone the monstruous Panaewa eruption, major summit shield building eruptions and the collapse of Mokuaweoweo so it is still a very impressive volcano when it gets most of the supply.

Without the shared supply I don’t think the alternation between Mauna Loa and Kilauea in activity can be explained.

I would give a depth of 3-5 km for most of the eruptions you have mentioned.

The difference is that kilaueas radial vents were shallow superficial vents branching off the upper part of the system like what happened on pu’u o’o, mauna loas radial vents are deep structures which erupt lava that is from below the rift system, 1859 erupted picrite olivine basalt that is derived from deep within the volcano. This is not very analogous. Mauna loa is also not growing anymore, its growth pretty much stopped around the end of the pleistocene, which is also when kilauea started growing very fast. Mauna loa has only really had two periods in the holocene where it was really active, a poorly known period around 10,000 years ago where it was resurfaced a lot, followed by 2000 years of very little activity and then another big burst about 1500 years ago ending with the pana’ewa flow. There have been other smaller sequences like what happened in historical time but kilauea has been far more active during the holocene, although by world standards mauna loa is still exceptionally active. It is also notable that in between these periods between 7000 and 2000 years ago was when most of the lava on the puna ridge was erupted, and since then there have been no major eruptions there at all and the ocean above even the nearest bit of the ridge is 500 meters deep. Something seems to be stopping eruptions from happening underwater on kilauea.

Also assuming pana’ewa is about 20 meters thick on average and has an area of about 200 km2 then it would have a volume of 4 km3, but it is probably a lot thicker than that at the delta and so it could be even more than that but by how much I dont know. That flow is like erupting 4 times the volume of the recent eruption in probably about the same time, this eruption would have been almost like an Icelandic flood basalt, I think it also formed a prominent cinder cone which is often visible in some of the pictures taken of kilauea when looking towards hilo.
Panaewa is probably the biggest single lava flow erupted in hawaii during the holocene, other eruptions have easily passed that but all of them were long lasting and the closest that has been observed happened this year. Still, if things keep going the way they have been with kilauea then the current very voluminous phase of rift activity could be terminated by a flow similar to panaewa, though maybe it would be partly submarine, and that could happen relatively soon probably this century or even this decade. Either way it is not a very good idea to build a big house in lower puna.

Finalizing my excursions around Teide on Tenerife. The collapse of the northwestern section The Las Canadas caldera into the sea around 150-200.000 years ago must have caused a tremedous zunami northwest into the north atlantic ocean. The scars in the landscape are still there. Now I wonder if the Oraefajökull volcano in southern Iceland could suffer a similar collapse? It is high and very steep One could imagine an enormous pressure from the inside glacier…. Scary perspective but is the real risk?

Probably you are right. The risk is small. However, the distance from Oraefajökul to the sea is 10-13 Km towards southwest. The same distance between Las Canadas collapsed north eastern rim and the sea..

I would worry more about stratovolcanoes with very steep slopes like Fuego, or think of the volcanoes of the Central Kamchatka Depression of which several have suffered large flank failures through their eruptive history. Those are even more common than collapses of shield volcanoes in oceanic islands though these last ones are more massive, Las Cañadas was 4000 masl and 7000 m above the ocean floor.

Hard to call. vehicular NOx release can vary quite a bit depending on engine tuning. Flame quenched Hydrocarbon residue can be reduced via catalytic converters, and excess SO2 from diesels can be reduced via urea processing in the exhaust, but NOx production peak is just shy of ideal air/fuel ratio on the lean side.

Great song, and although it’s a cover version, my favourite is the Fureys’ version.
I was definitely NOT a fan of the version promoted by the Royal British Legion by Jeff Beck and Joss Stone a couple of years ago. It left out the last verse, without which the song loses most of its meaning and impact.

Anyway. Tjornes fracture zone. Approx 115 quakes at a variety of depths and magnitudes (up to 3 ) since Friday, as of this moment (9.53 am UK time) . I know the area throws little tantrums from time to time as a part of its normal routine behaviour, but this seems quite a prolonged and vigorous episode. Is it something we need to be watching?

And apropos of nothing at all except maybe my smugness….
I went to my local pub a few days ago to watch folk duo A.J. Clarke and Dave Pegg (ex of Jethro Tull, now of Fairport Convention). I knew they would have a support act…. But I wasn’t expecting it to be Robert Plant and friends ! The audience also had more than a smattering of musical luminaries such as Bev Bevan (ex of ELO).

For being at that location this is not that much. I have seen four or five larger swarms there, and written about it a few times.
Sooner or later something out there will erupt, but it will probably be quite memorable on the SIL-plots.